(CNN) - Deputy Attorney General Rod Rosenstein defended his handling of the Russia investigation Thursday evening, recalling how he had promised to "do it right" during his Senate confirmation hearing and "take it to the appropriate conclusion," while taking pointed swipes at what he called "mercenary critics," politicians and the news media.

"It's not our job to render conclusive factual findings. We just decide whether it is appropriate to file criminal charges," Rosenstein said, speaking at a dinner in New York where he was honored by the Armenian Bar Association.

The redacted report released last week concluding special counsel Robert Mueller's investigation indicated that prosecutors ultimately did not make a decision on whether President Donald Trump had obstructed justice. But prosecutors did not exonerate him of criminal conduct, and determined that Congress still has the ability to find he obstructed justice.

Rosenstein went on to argue Thursday night that "some critical decisions" had been made before his tenure as the deputy attorney general. The previous administration "chose not to publicize the full story about Russian computer hackers and social media trolls" but the story later leaked to the media, he argued, and then-FBI Director James Comey then told Congress there was a counterintelligence investigation and alleged that Trump "pressured him to close the investigation."

"So that happened," Rosenstein said to laughter from the audience, before highlighting Mueller's findings of extensive Russian interference in the 2016 presidential election.

"The bottom line is that there was overwhelming evidence that Russian operatives had hacked American computers and defrauded American citizens, and that was only the tip of the iceberg of a comprehensive Russian strategy to influence elections, promote social discord and undermine America," he added.

Rosenstein stood by his decision to appoint Mueller, despite the fact that "not everybody was happy with my decision, in case you didn't notice" -- a possible reference to Trump's vocal and long-standing misgivings about the need for and motivations of the special counsel's team.

"You just need to accept that politicians need to evaluate everything in terms of the immediate political impact," Rosenstein added.

He also addressed reports of his emotions getting the better of him at stressful moments during the investigation, saying that one "silly question that I get from reporters" is whether it's true that he ever got angry.

"Heck, yes, didn't you?" he said.

Finally he addressed his "deadpan" facial expressions at Attorney General William Barr's news conference last week just prior to the report's release.

"The answer is, I was thinking, 'My job is to stand here with a deadpan expression,' " Rosenstein joked, adding, "Can you imagine if I did anything other than a deadpan reaction?"

Rosenstein also mentioned that he would be leaving the Department of Justice "next month." He was originally expected to leave earlier this year, but the departure date has been something of a moving target, as CNN has previously reported. Jeffrey Rosen, the deputy transportation secretary, who Trump nominated to replace Rosenstein, is still awaiting a vote on his confirmation in the Senate.